msm: acpuclock: Add a null check for acpuclk_data
msm: acpuclock: Add a null check for acpuclk_data

If acpuclock fails to probe before a client calls acpuclk_get_rate,
a null dereference will occur. Fix this by adding the appropriate
checks.

Change-Id: If873a64711e9cc807b1734996f7c9358bb08161a
Signed-off-by: Vikram Mulukutla <577f74ec3f2c8a155237d5ad42a70103d17f8313@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas